Change management is critical and challenging in the development and maintenance of service-based applications and information systems due to the distributed and dynamic nature of services. This paper proposes an approach for facilitating the change impact analysis in a service oriented environment. This research focuses on a typical scenario that multiple services are supported by a single business process. The change impact is analyzed based on the study of the dependency between services and business processes. Types of changes and change impact patterns are identified on the foundation of a service oriented business process model. These change types and the impact patterns can be used to enable the analysis of change propagation of the business process and associated services. Algorithms for computing impact scopes of changes are provided.